/*
 * @(#)DNSNameAttribute.java
 *
 * Copyright 2005 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistribution of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 * 
 *   2. Redistribution in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed or intended for use in
 * the design, construction, operation or maintenance of any nuclear facility.
 */

package org.wso2.balana.attr;

import org.wso2.balana.ParsingException;

import java.net.URI;

import org.w3c.dom.Node;

/**
 * Represents the DNSName datatype introduced in XACML 2.0. All objects of this
 * class are immutable and all methods of the class are thread-safe.
 * 
 * @since 2.0
 * @author Seth Proctor
 */
public class DNSNameAttribute extends AttributeValue {

	/**
	 * Official name of this type
	 */
	public static final String identifier = "urn:oasis:names:tc:xacml:2.0:data-type:dnsName";

	/**
	 * URI version of name for this type
	 * <p>
	 * This field is initialized by a static initializer so that we can catch
	 * any exceptions thrown by URI(String) and transform them into a
	 * RuntimeException, since this should never happen but should be reported
	 * properly if it ever does.
	 */
	private static URI identifierURI;

	/**
	 * RuntimeException that wraps an Exception thrown during the creation of
	 * identifierURI, null if none.
	 */
	private static RuntimeException earlyException;

	/**
	 * Static initializer that initializes the identifierURI class field so that
	 * we can catch any exceptions thrown by URI(String) and transform them into
	 * a RuntimeException. Such exceptions should never happen but should be
	 * reported properly if they ever do.
	 */
	static {
		try {
			identifierURI = new URI(identifier);
		} catch (Exception e) {
			earlyException = new IllegalArgumentException();
			earlyException.initCause(e);
		}
	};

	// the required hostname
	private String hostname;

	// the optional port range
	private PortRange range;

	// true if the hostname starts with a '*'
	private boolean isSubdomain = false;

	/**
	 * Creates the new <code>DNSNameAttribute</code> with only the required
	 * hostname component.
	 * 
	 * @param hostname
	 *            the host name component of the address
	 * 
	 * @throws ParsingException
	 *             if the hostname is invalid
	 */
	public DNSNameAttribute(String hostname) throws ParsingException {
		this(hostname, new PortRange());
	}

	/**
	 * Creates the new <code>DNSNameAttribute</code> with the optional port
	 * range component.
	 * 
	 * @param hostname
	 *            the host name component of the address
	 * @param range
	 *            the port range
	 * 
	 * @throws ParsingException
	 *             if the hostname is invalid
	 */
	public DNSNameAttribute(String hostname, PortRange range)
			throws ParsingException {
		super(identifierURI);

		// shouldn't happen, but just in case...
		if (earlyException != null)
			throw earlyException;

		// verify that the hostname is valid before we store it
		if (!isValidHostName(hostname))
			System.out.println("FIXME: throw error about bad hostname");

		// see if it started with a '*' character
		if (hostname.charAt(0) == '*')
			this.isSubdomain = true;

		this.hostname = hostname;
		this.range = range;
	}

	/**
	 * Private helper that tests whether the given string is valid.
	 */
	private boolean isValidHostName(String hostname) {
		/*
		 * hostname = *( domainlabel "." ) toplabel [ "." ] domainlabel =
		 * alphanum | alphanum *( alphanum | "-" ) alphanum toplabel = alpha |
		 * alpha *( alphanum | "-" ) alphanum
		 */

		String domainlabel = "\\w[[\\w|\\-]*\\w]?";
		String toplabel = "[a-zA-Z][[\\w|\\-]*\\w]?";
		String pattern = "[\\*\\.]?[" + domainlabel + "\\.]*" + toplabel
				+ "\\.?";

		return hostname.matches(pattern);
	}

	/**
	 * Returns a new <code>DNSNameAttribute</code> that represents the name at a
	 * particular DOM node.
	 * 
	 * @param root
	 *            the <code>Node</code> that contains the desired value
	 * 
	 * @return a new <code>DNSNameAttribute</code> representing the appropriate
	 *         value (null if there is a parsing error)
	 * 
	 * @throws ParsingException
	 *             if the hostname is invalid
	 */
	public static DNSNameAttribute getInstance(Node root)
			throws ParsingException {
		return getInstance(root.getFirstChild().getNodeValue());
	}

	/**
	 * Returns a new <code>DNSNameAttribute</code> that represents the name
	 * indicated by the <code>String</code> provided.
	 * 
	 * @param value
	 *            a string representing the name
	 * 
	 * @return a new <code>DNSNameAttribute</code>
	 * 
	 * @throws ParsingException
	 *             if the hostname is invalid
	 */
	public static DNSNameAttribute getInstance(String value)
			throws ParsingException {
		int portSep = value.indexOf(':');

		if (portSep == -1) {
			// there is no port range, so just use the name
			return new DNSNameAttribute(value);
		} else {
			// split the name and the port range
			String hostname = value.substring(0, portSep);
			PortRange range = PortRange.getInstance(value.substring(
					portSep + 1, value.length()));
			return new DNSNameAttribute(hostname, range);
		}
	}

	/**
	 * Returns the host name represented by this object.
	 * 
	 * @return the host name
	 */
	public String getHostName() {
		return hostname;
	}

	/**
	 * Returns the port range represented by this object which will be unbound
	 * if no range was specified.
	 * 
	 * @return the port range
	 */
	public PortRange getPortRange() {
		return range;
	}

	/**
	 * Returns true if the leading character in the hostname is a '*', and
	 * therefore represents a matching subdomain, or false otherwise.
	 * 
	 * @return true if the name represents a subdomain, false otherwise
	 */
	public boolean isSubdomain() {
		return isSubdomain;
	}

	/**
	 * Returns true if the input is an instance of this class and if its value
	 * equals the value contained in this class.
	 * 
	 * @param o
	 *            the object to compare
	 * 
	 * @return true if this object and the input represent the same value
	 */
	public boolean equals(Object o) {
		if (!(o instanceof DNSNameAttribute))
			return false;

		DNSNameAttribute other = (DNSNameAttribute) o;

		if (!hostname.toUpperCase().equals(other.hostname.toUpperCase()))
			return false;

		if (!range.equals(other.range))
			return false;

		return true;
	}

	/**
	 * Returns the hashcode value used to index and compare this object with
	 * others of the same type.
	 * 
	 * @return the object's hashcode value
	 */
	public int hashCode() {

		return 0;
	}

	/**
	 * Converts to a String representation.
	 * 
	 * @return the String representation
	 */
	public String toString() {
		return "DNSNameAttribute: \"" + encode() + "\"";
	}

	/**
     *
     */
	public String encode() {
		if (range.isUnbound())
			return hostname;

		return hostname + ":" + range.encode();
	}

}
